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We consider the shift operator $M_z$, defined on the Bloch space and the little Bloch space and we study the corresponding lattice of invariant subspaces. The index of a closed invariant subspace $E$ is defined as $\text{ind}(E) =…

Functional Analysis · Mathematics 2024-09-06 Nikiforos Biehler

We show a few fixed point theorems for semigroups acting on weakly compact convex subsets of Banach spaces when $LUC(S), AP(S), WAP(S)$ or $WAP(S)\cap LUC(S)$ have a left invariant mean. In particular, we give a characterization of…

Functional Analysis · Mathematics 2016-12-20 Andrzej Wiśnicki

We prove that in Lipschitz-free spaces the strong diameter two property, the diameter two property, and the local diameter two property coincide with their corresponding attaining variants.

Functional Analysis · Mathematics 2026-04-08 Jaan Kristjan Kaasik

Having been unclear how to define that a domain is strictly pseudoconvex in the infinite-dimensional setting, we develop a general theory having Banach spaces in mind. We first focus on finite dimension and eliminate the need of two degrees…

Complex Variables · Mathematics 2022-08-15 Sofia Ortega Castillo

This paper provides conditions (i) to distinguish weak supercyclicity form supercyclicity for operators acting on normed and Banach spaces, and also (ii) to ensure when weak supercyclicity implies weak stability.

Functional Analysis · Mathematics 2021-01-26 C. S. Kubrusly , B. P. Duggal

In this work, we study the non rough norms in Banach spaces with small diameter properties, namely the Ball Dentable Property (BDP), the Ball Huskable Property (BHP) and the Ball Small Combination of Slice Property (BSCSP). We introduce two…

Functional Analysis · Mathematics 2023-07-10 Sudeshna Basu , Susmita Seal

We introduce the notion of domains with uniform squeezing property, study various analytic and geometric properties of such domains and show that they cover many interesting examples, including Teichmuller spaces and Hermitian symmetric…

Complex Variables · Mathematics 2009-06-26 Sai-Kee Yeung

We discuss the connection between the expansion of small sets in graphs, and the Schatten norms of their adjacency matrix. In conjunction with a variant of the Azuma inequality for uniformly smooth normed spaces, we deduce improved bounds…

Combinatorics · Mathematics 2010-09-30 Assaf Naor

We study the best coapproximation problem in Banach spaces, by using Birkhoff-James orthogonality techniques. We introduce two special types of subspaces, christened the anti-coproximinal subspaces and the strongly anti-coproximinal…

Functional Analysis · Mathematics 2024-08-14 Shamim Sohel , Souvik Ghosh , Debmalya Sain , Kallol Paul

We study a uniform version of the strong diameter two property. In particular, we find a characterisation that does not involve ultrafilters and we use it to provide some examples of spaces with this uniform property that do not follow from…

Functional Analysis · Mathematics 2025-12-15 Esteban Martínez Vañó , Abraham Rueda Zoca

The maximal roundness of a metric space is a quantity that arose in the study of embeddings and renormings. In the setting of Banach spaces, it was shown by Enflo that roundness takes on a much simpler form. In this paper we provide simple…

Functional Analysis · Mathematics 2021-09-16 Alireza Amini-Harandi , Ian Doust , Gavin Robertson

This paper focuses on properties of \partial-biLipschitz mappings which were recently introduced by Bulter. We establish several characterizations for the class of \partial-biLipschitz mappings between domains in quasiconvex metric spaces.…

Complex Variables · Mathematics 2022-02-16 Tiantian Guan , Saminathan Ponnusamy , Qingshan Zhou

In this paper we show that if $(y_n)$ is a seminormalized sequence in a Banach space which does not have any weakly convergent subsequence, then it contains a wide-$(s)$ subsequence $(x_n)$ which admits an equivalent convex basic sequence.…

Functional Analysis · Mathematics 2018-03-26 C. S. Barroso , V. Ferreira

We obtain a result in the spirit of the well-known W. Schachermeyer and H. P. Rosenthal research about the equivalence between Radon-Nikodym and Krein-Milman properties, by showing that, for closed, bounded and convex subsets C of a…

Functional Analysis · Mathematics 2023-05-31 Ginés López-Pérez , Rubén Medina

We prove the following result: For each closed $n$-dimensional manifold $M$ in a (finite or infinite-dimensional) Banach space $B$, and each positive real $m\leq n$ there exists a pseudomanifold $W^{n+1}\subset B$ such that $\partial…

Metric Geometry · Mathematics 2025-04-18 Sergey Avvakumov , Alexander Nabutovsky

Let $X$ and $Y$ be separable Banach spaces. Suppose $Y$ either has a shrinking basis or $Y$ is isomorphic to $C(2^\mathbb{N})$ and $A$ is a subset of weakly compact operators from $X$ to $Y$ which is analytic in the strong operator…

Functional Analysis · Mathematics 2013-04-15 Kevin Beanland , Daniel Freeman

We characterize the relatively compact subsets of $L^1\left(\| m \| \right),$ the quasi-Banach function space associated to the semivariation of a given vector measure $m$ showing that the strong connection between compactness, uniform…

Functional Analysis · Mathematics 2019-10-30 Ricardo del Campo , Antonio Fernández , Fernando Mayoral , Francisco Naranjo

Motivated by the equivalent definition of a continuous operator between Banach spaces in terms of weakly null nets, we introduce two types of continuous operators between Banach lattices using unbounded absolute weak convergence. We…

Functional Analysis · Mathematics 2020-04-07 Omid Zabeti

Let $E$ be a Banach space such that $E'$ has the Radon-Nikod\'ym property. The aim of this work is to connect relative weak compactness in the $E$-valued martingale Hardy space $H^{1}(\mu,E)$ to a convex compactness criterion in a weaker…

Functional Analysis · Mathematics 2024-10-21 Vasily Melnikov

We prove that every Banach space containing a subspace isomorphic to $\co$ fails the fixed point property. The proof is based on an amalgamation approach involving a suitable combination of known results and techniques, including James's…

Functional Analysis · Mathematics 2018-08-15 Cleon S. Barroso